VBA Count Down Timer

I have converted some code that works like a countdown timer and is perfect for my needs apart from one small aspect - it counts down in seconds only, not minutes and seconds. The format I am looking for is X:yy where x is minutes and y is seconds, eg 180 seconds = 3:00. Is there a simple format I can add to a cell that will do the trick? EDIT:I think the Dim at the top of this code is causing the problems as I don't really want to show the date - just minutes and seconds counting down. A sample workbook is included - code is in Thisworkbook, Sheet1 and module1.

Dim CountDown As Date
Sub Timer()
CountDown = Now + TimeValue("00:00:01")
Application.OnTime CountDown, "Reset"
End Sub
Sub Reset()
Dim count As Range
Set count = [A1] ' A1 contains the number of seconds for the countdown.
count.Value = count.Value - 1
If count <= 0 Then
MsgBox "Countdown complete."
Exit Sub
End If
Call Timer
End Sub
Sub DisableTimer()
On Error Resume Next
Application.OnTime EarliestTime:=CountDown, Procedure:="Reset", Schedule:=False
End Sub